CN113161146A

CN113161146A - Ceramic electronic component and method for manufacturing ceramic electronic component

Info

Publication number: CN113161146A
Application number: CN202010667763.7A
Authority: CN
Inventors: 姜晟馨; 曹钟贤; 赵志弘; 赵沆奎; 沈载植; 金龙寅; 李相录
Original assignee: Samsung Electro Mechanics Co Ltd
Current assignee: Samsung Electro Mechanics Co Ltd
Priority date: 2020-01-07
Filing date: 2020-07-13
Publication date: 2021-07-23
Also published as: KR20210088910A; KR20220116106A; JP2021111768A; KR102437804B1; US11569037B2; KR102584977B1; US11948752B2; US20210210288A1; US20230129225A1

Abstract

The present disclosure provides a ceramic electronic component including a main body including a dielectric layer and an internal electrode, and an external electrode disposed on the main body and connected to the internal electrode, and a method of manufacturing the ceramic electronic component. The dielectric layer includes a plurality of dielectric crystal grains, and at least one of the plurality of dielectric crystal grains has a core-double shell structure having a core and a double shell. The double shell includes a first shell surrounding at least a portion of the core and a second shell surrounding at least a portion of the first shell, and a concentration of the rare earth element included in the second shell is greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

Description

Ceramic electronic component and method for manufacturing ceramic electronic component

This application claims the benefit of priority of korean patent application No. 10-2020-.

Technical Field

The present disclosure relates to a ceramic electronic component and a method of manufacturing the ceramic electronic component.

Background

In general, a ceramic electronic component (such as a capacitor, an inductor, a piezoelectric element, a varistor, a thermistor, etc.) using a ceramic material may include a ceramic body made of a ceramic material, internal electrodes formed in the ceramic body, and external electrodes disposed on a surface of the ceramic body to be connected to the internal electrodes.

Multilayer ceramic capacitors (MLCCs), a type of ceramic electronic component, are being developed to have increased capacity through ultra-thinning of their layers.

A high-capacity multilayer ceramic capacitor (MLCC) may include barium titanate (BaTiO) as a main material forming a body₃) And nickel as a base material of the internal electrode.

Such bodies are typically fired in a reducing atmosphere. In this case, the dielectric in the body should be resistant to reduction.

However, due to the inherent properties of the oxide, oxygen in the oxide may escape during the firing operation in a reducing atmosphere to generate oxygen holes and electrons. Therefore, reliability and Insulation Resistance (IR) thereof may be deteriorated.

In order to solve the problem, a method has been proposed in which a rare earth element (such as Dy, Y, Ho, or the like) is added to suppress the generation of oxygen holes, the mobility of the oxygen holes is reduced, and the generated electrons are removed by adding a transition metal.

However, there is still a problem in that the above method may not be effective when layers in the multilayer ceramic capacitor are thinned to have a relatively high capacity or when a relatively high voltage is used therein under a more severe use environment.

Further, when a rare earth element or a transition element is added by the above method, high-temperature life characteristics may be deteriorated, or Temperature Coefficient of Capacitance (TCC) characteristics according to temperature change may be deteriorated.

Disclosure of Invention

An aspect of the present disclosure is to provide a ceramic electronic component capable of improving reliability and a method of manufacturing the same.

An aspect of the present disclosure is to provide a ceramic electronic component capable of improving Temperature Coefficient of Capacitance (TCC) characteristics and a method of manufacturing the same.

An aspect of the present disclosure is to provide a ceramic electronic component capable of improving high-temperature lifespan characteristics and a method of manufacturing the same.

An aspect of the present disclosure is to provide a ceramic electronic component capable of improving a dielectric constant and a method of manufacturing the same.

However, the purpose of the present disclosure is not limited to the above description, and will be more easily understood in describing specific embodiments of the present disclosure.

According to an aspect of the present disclosure, a ceramic electronic component includes a body including a dielectric layer and an inner electrode, and an outer electrode disposed on the body and connected to the inner electrode. The dielectric layer includes a plurality of dielectric crystal grains, and at least one of the plurality of dielectric crystal grains has a core-double shell structure having a core and a double shell. In addition, the double shell includes a first shell surrounding at least a portion of the core and a second shell surrounding at least a portion of the first shell, and a concentration of the rare earth element included in the second shell is greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

According to another aspect of the present disclosure, a method of manufacturing a ceramic electronic component includes: preparing ceramic green sheets each including a base material powder having a core-shell structure having a core and a shell, and the shell including a rare earth element, and a secondary component added to the base material powder. A conductive paste for internal electrodes is printed on the ceramic green sheets, and the printed ceramic green sheets are stacked to prepare a stack. The stacked body is fired to prepare a body including the dielectric layers and the internal electrodes, and the external electrodes are formed on the body. The amount of the rare earth element included in the base material powder is more than 0.6 times and less than 2.4 times the amount of the rare earth element included in the secondary component.

According to another aspect of the present disclosure, a ceramic electronic component includes a main body including first and second internal electrodes that are stacked on each other with a dielectric layer disposed therebetween. In a region of the dielectric layer disposed 0.41 μm or less from both the first and second internal electrodes, 50% or more of the total number of dielectric grains in the dielectric layer have a core-double shell structure having a core, a first shell having a different composition from the core and surrounding at least a portion of the core, and a second shell having a different composition from the first shell and surrounding at least a portion of the first shell.

According to another aspect of the present disclosure, a ceramic electronic component includes a main body including first and second internal electrodes that are stacked on each other with a dielectric layer disposed therebetween. In a region of the dielectric layer disposed 0.41 μm or less from both the first and second internal electrodes, at least one of the dielectric crystal grains of the dielectric layer has a core-shell structure having a core and a first shell surrounding at least a portion of the core and having a concentration of the rare earth element higher than that of the core.

Drawings

The above and other aspects, features and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a perspective view schematically illustrating a ceramic electronic component according to an embodiment of the present disclosure.

Fig. 2 is a schematic sectional view taken along line I-I' of fig. 1.

Fig. 3 is a schematic sectional view taken along line II-II' of fig. 1.

Fig. 4 is an exploded perspective view schematically illustrating a body in which dielectric layers and inner electrodes are stacked according to an embodiment of the present disclosure.

Fig. 5 is an enlarged view of the region P of fig. 2.

Fig. 6 is a schematic view showing a crystal grain having a core-double shell structure.

Fig. 7 shows the intensity of Dy measured as a result of XRF EDS line analysis of grains having a core-double shell structure of test No. 9 (inventive example).

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to specific embodiments and drawings. However, the embodiments of the present disclosure may be modified to have various other forms, and the scope of the present disclosure is not limited to the embodiments described below. Furthermore, embodiments of the present disclosure may be provided to more fully describe the present disclosure to those of ordinary skill in the art. Therefore, the shapes and sizes of elements in the drawings may be exaggerated for clarity of description, and elements denoted by the same reference numerals in the drawings may be the same elements.

In the drawings, portions irrelevant to the description will be omitted for clarity of the present disclosure, and the thickness may be exaggerated to clearly show layers and regions. Further, throughout the specification, when an element is referred to as being "comprising" or "includes" an element, it means that the element may also include other elements, unless specifically stated otherwise, without departing from the scope of the description.

In the drawings, the X direction may be defined as a second direction, an L direction, or a length direction; the Y direction may be defined as a third direction, a W direction, or a width direction; and the Z direction may be defined as a first direction, a stacking direction, a T direction, or a thickness direction.

Ceramic electronic component

Fig. 2 is a schematic sectional view taken along line I-I' of fig. 1.

Fig. 3 is a schematic sectional view taken along line II-II' of fig. 1.

Fig. 5 is an enlarged view of the region P of fig. 2.

Hereinafter, the ceramic electronic component 100 according to an embodiment of the present disclosure will be described in detail with reference to fig. 1 to 6. Further, a multilayer ceramic capacitor will be described as an example of the ceramic electronic component, but the present disclosure is not limited thereto. In addition, ceramic electronic components (such as capacitors, inductors, piezoelectric elements, varistors, thermistors, and the like) using ceramic materials can also be applied.

The ceramic electronic component 100 according to an embodiment of the present disclosure includes: a body 110 including a dielectric layer 111 and

internal electrodes

121 and 122; and

outer electrodes

131 and 132 disposed on the body 110 and connected to the

inner electrodes

121 and 122, respectively, wherein the dielectric layer 111 includes a plurality of

dielectric grains

10a, 10b, and 10C, wherein at least one of the plurality of dielectric grains has a core-double shell structure having a core C and a double shell, wherein the double shell includes a first shell S1 surrounding at least a portion of the core C and a second shell S2 surrounding at least a portion of the first shell S1, and wherein a concentration of the rare earth element included in the second shell S2 is greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell S1.

In the body 110, a plurality of dielectric layers 111 may be alternately stacked with the

internal electrodes

121 or 122. In addition, the

internal electrodes

121 and 122 may be alternately stacked, and a dielectric layer is interposed between the

internal electrodes

121 and 122.

Although the specific shape of the body 110 is not particularly limited, as illustrated, the body 110 may have a hexahedral shape or the like. The body 110 may not have a perfect hexahedral shape including a perfect straight line due to shrinkage of the ceramic powder contained in the body 110 during a firing process, but may generally have a substantially hexahedral shape.

The main body 110 may have: a first surface 1 and a second surface 2 opposing each other in a thickness direction (Z direction); a third surface 3 and a fourth surface 4 connected to the first surface 1 and the second surface 2 and opposed to each other in a length direction (X direction); and fifth and sixth surfaces 5 and 6 connected to the first and

second surfaces

1 and 2, connected to the third and

fourth surfaces

3 and 4, and opposed to each other in the width direction (Y direction).

The plurality of dielectric layers 111 forming the body 110 may be in a sintered state, and boundaries between adjacent dielectric layers 111 may be integrated to such an extent that it is difficult to identify individual layers without using a Scanning Electron Microscope (SEM).

Referring to fig. 5, each dielectric layer 111 may include a plurality of

dielectric grains

10a, 10b, and 10c, and at least one of the plurality of dielectric grains may be a dielectric grain 10a having a core-double shell structure.

Referring to fig. 6, the dielectric grain 10a having a core-double shell structure may include a first shell S1 surrounding at least a portion of the core C and a second shell S2 surrounding at least a portion of the first shell S1.

The development of multilayer ceramic capacitors (MLCCs), an example of a common ceramic electronic component, has focused on the capacity increase of MLCCs and the ultra-thinning of layers. With the increase in capacity and the ultra-thinning of layers, it has become increasingly difficult to ensure the withstand voltage characteristics of the dielectric layers in the multilayer ceramic capacitor, and the increase in the defect rate due to the deterioration of the insulation resistance of the dielectric layers has become a problem.

In order to solve the problems, a method of adding a rare earth element (such as Dy, Y, Ho, or the like) to suppress the generation of oxygen holes, reducing the mobility of the oxygen holes, and removing the generated electrons by adding a transition metal has been proposed.

However, when the layers in the multilayer ceramic capacitor are thinned to have a relatively high capacity or when a relatively high voltage is used therein under a more severe use environment, there have been cases in which: simple addition of rare earth elements or transition elements may not sufficiently solve the above problems, or a high temperature life characteristic or a Temperature Coefficient of Capacitance (TCC) characteristic according to temperature change may not have a desired level.

Accordingly, in the present disclosure, at least one of the plurality of dielectric grains has a core-double shell structure, and in the core-double shell structure, a ratio of a concentration of the rare earth element included in the first shell to a concentration of the rare earth element included in the second shell may be controlled to ensure better high-temperature lifetime characteristics and TCC characteristics.

The rare earth elements included in the first and second shells S1 and S2 may be substantially substituted by ABO₃The A site or B site of the perovskite structure represented to form a shell region. The shell region may act as a barrier to prevent electrons from flowing at the grain boundaries of the dielectric grains, thereby preventing leakage current.

In addition, since the shells S1 and S2 have a double structure composed of the first shell S1 and the second shell S2 using different rare earth element concentrations, high temperature life characteristics and TCC characteristics can be further improved.

The rare earth element may be absent or present in the core C, or only a trace amount of the rare earth element may be present or present in the core C. Therefore, the concentration of the rare earth element included in the core C may be 0.1 times or less the concentration of the rare earth element included in the first shell S1.

In addition, since the concentration of the rare earth element rapidly changes at the boundary between the core C and the first shell S1 and rapidly changes at the boundary between the first shell S1 and the second shell S2, the core C, the first shell S1, and the second shell S2 can be easily distinguished and confirmed through TEM-EDS analysis.

As shown in fig. 5 and 6, the first shell S1 may be disposed to cover the entire surface of the core C, and the second shell S2 may be disposed to cover the entire surface of the first shell S1. The first shell may not cover a portion of the surface of the core (e.g., the first shell may cover less than the entire surface of the core), and the second shell may be present in a form that does not cover a portion of the surface of the first shell (e.g., the second shell may cover less than the entire surface of the first shell).

In this case, the first shell S1 may be disposed to cover at least 90% (area) of the surface of the core, and the second shell S2 may be disposed to cover at least 90% (area) of the surface of the first shell S1. When the first shell S1 is disposed to cover less than 90% (area) of the surface of the core, and/or the second shell S2 is disposed to cover less than 90% (area) of the surface of the first shell S1, the effect of improving reliability according to the present disclosure may be insufficient.

The concentration of the rare earth element included in the second shell S2 may be more than 1.3 times and less than 3.8 times the concentration of the rare earth element included in the first shell S1.

When the concentration of the rare earth element included in the second shell S2 is 1.3 times or less the concentration of the rare earth element included in the first shell S1, the concentration of the rare earth element included in the first shell S1 may be similar to the concentration of the rare earth element included in the second shell S2. Therefore, the effect of improving reliability according to the core-double shell structure may be insufficient.

When the concentration of the rare earth element included in the second shell S2 is 3.8 times or more the concentration of the rare earth element included in the first shell S1, the concentration of the rare earth element included in the second shell S2 may become too high. Therefore, since a second phase may be formed from the rare earth element, reliability may be deteriorated.

Referring to fig. 6, a distance (LS2) corresponding to a thickness of the second shell along a straight line connecting α and β may be greater than 4% and less than 25% of a distance between α and β, where α denotes a center of the core-double shell structure in a cross-section of the core-double shell structure, and β denotes a point on a surface of the second shell farthest from α. In this case, α may refer to the center of gravity of the dielectric crystal grain in the cross section.

When the distance (LS2) corresponding to the thickness of the second shell along the straight line connecting α and β is 4% or less, the effect of improving reliability may be insufficient, and the effect of improving high-temperature lifetime characteristics and dielectric constant may be deteriorated.

When the distance (LS2) corresponding to the thickness of the second case along the straight line connecting α and β is 25% or more, high temperature lifetime characteristics may be deteriorated or Temperature Coefficient of Capacitance (TCC) characteristics according to temperature change may be deteriorated.

Therefore, it is preferable that the distance (LS2) corresponding to the thickness of the second shell along the straight line connecting α and β is greater than 4% and less than 25%, more preferably, greater than or equal to 4.5% and less than or equal to 24%, even more preferably, greater than or equal to 5% and less than or equal to 20%.

In this case, a distance (LS1) corresponding to the thickness of the first shell along a straight line connecting α and β may be greater than or equal to 5% and less than or equal to 30% of the distance between α and β.

When the distance (LS1) corresponding to the thickness of the first shell along the straight line connecting α and β is less than 5%, it may be difficult to achieve the double shell structure. When the distance (LS1) corresponding to the thickness of the first shell along the straight line connecting α and β exceeds 30%, it may be difficult to ensure reliability.

In addition, when the distance/thickness of the first case (LS1) is greatly different from the distance/thickness of the second case (LS2), it may be difficult to simultaneously improve the high temperature life characteristic and the TCC characteristic. Accordingly, the distance/thickness (LS1) along the straight line connecting α and β corresponding to the first shell may be 0.5 to 1.5 times the distance/thickness (LS2) along the straight line connecting α and β corresponding to the second shell.

Referring to fig. 5, the dielectric layer 111 may include dielectric crystal grains 10b having a core-shell structure in addition to the dielectric crystal grains 10a having a core-double shell structure. Thus, at least one of the plurality of dielectric grains may be a dielectric grain 10b having a core-shell structure. The dielectric grain 10b having the core-shell structure may include a core 10b1 and a shell 10b2 surrounding at least a portion of the core 10b 1. In this case, the shell 10b2 of the core-shell structure may have an amount of rare earth different from that of the shells S1 and S2 of the core-double shell structure. The present disclosure is not limited thereto, and the core-shell structured shell 10b2 may have the same amount of rare earth as one of the shells S1 and S2 of the core-double shell structure.

In addition, the dielectric layer 111 may include the dielectric crystal grain 10c without a separate shell.

In this case, among the plurality of

dielectric grains

10a, 10b, and 10c, the number of dielectric grains 10a having a core-double shell structure may be 50% or more. In this case, the ratio of the number of dielectric crystal grains having a core-double shell structure may be measured in an image obtained by scanning a cross section of the dielectric layer by a Transmission Electron Microscope (TEM).

When the number of the dielectric grains having the core-double shell structure among the plurality of dielectric grains is less than 50%, the effect of improving the high temperature lifetime characteristic and the TCC characteristic may be insufficient.

In addition, the dielectric layer 111 may include a dielectric layer having a composition consisting of ABO₃The perovskite structure material is shown as the main component.

For example, the dielectric layer 111 may comprise BaTiO₃、(Ba,Ca)(Ti,Ca)O₃、(Ba,Ca)(Ti,Zr)O₃、Ba(Ti,Zr)O₃And (Ba, Ca) (Ti, Sn) O₃As a main component.

More specifically, for example, the dielectric layer 111 may comprise BaTiO₃、(Ba_1-xCa_x)(Ti_1-yCa_y)O₃(wherein x is 0-0.3, y is 0-0.1), (Ba_1-xCa_x)(Ti_1-yZr_y)O₃(wherein x is more than or equal to 0 and less than or equal to 0.3, y is more than or equal to 0 and less than or equal to 0.5), Ba (Ti)_1-yZr_y)O₃(wherein, 0<y is less than or equal to 0.5) and (Ba)_1-xCa_x)(Ti_1-ySn_y)O₃(wherein 0. ltoreq. x. ltoreq.0.3, and 0. ltoreq. y. ltoreq.0.1) as a main component.

In addition, the dielectric layer 111 may include an amount of the rare earth element in a range of 0.1 mol to 15 mol with respect to 100 mol of the main component.

When the amount of the rare earth element included in the dielectric layer 111 is less than 0.1 mol with respect to 100 mol of the main component, it may be difficult to achieve the core-double shell structure. When the amount of the rare earth element included in the dielectric layer 111 exceeds 15 mol with respect to 100 mol of the main component, the firing temperature may rapidly increase. Therefore, it may be difficult to obtain a dense microstructure.

In this case, the rare earth element may be one or more of lanthanum (La), yttrium (Y), actinium (Ac), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and ruthenium (Ru).

In addition, the minor component included in the dielectric layer 111 is not particularly limited except that a rare earth element should be included, and an appropriate element and amount of the element may be determined to obtain desired characteristics. For example, the dielectric layer 111 may include one or more of Mn, Cr, Ba, Si, Al, Mg, and Zr as a minor component in addition to the rare earth element.

The size of the dielectric grains is not particularly limited. For example, the average grain size of the dielectric grains in the dielectric layer 111 may be 50nm or more and 500nm or less.

When the average grain size is less than 50nm, there may be a problem in that the intended effect due to low dielectric constant and low grain growth rate may not be sufficient to achieve the intended effect. When the average grain size exceeds 500nm, capacity variation according to temperature and DC voltage may increase, and reliability may be reduced due to a decrease in the number of dielectric grains per unit volume of the dielectric layer.

The body 110 may include: a capacitance forming part a disposed in the body 110 and including first and second

internal electrodes

121 and 122, the first and second

internal electrodes

121 and 122 being arranged to face and overlap each other with the dielectric layer 111 interposed between the first and second

internal electrodes

121 and 122 to form a capacitance; and covering

portions

112 and 113 formed above and below the capacitance forming portion a.

In addition, the capacitance forming part a may be a part contributing to the capacitance formation of the capacitor, and may be formed by repeatedly and alternately stacking a plurality of the first and second

internal electrodes

121 and 122 with the dielectric layer 111 interposed between the first and second

internal electrodes

121 and 122.

The upper and

lower cover parts

112 and 113 may be formed by stacking a single dielectric layer or two or more dielectric layers on the upper and lower surfaces of the capacitance forming part, respectively, in the vertical direction, and may function to substantially prevent the internal electrodes from being damaged by external physical or chemical stress.

The upper and

lower covers

112 and 113 may not include an inner electrode and may include the same material as the dielectric layer 111.

For example, the upper and

lower caps

112 and 113 may include a ceramic material, e.g., may include barium titanate (BaTiO)₃) A base ceramic material.

In addition,

edge portions

114 and 115 may be provided on the side surfaces of the capacitance forming portion a.

The

edge portions

114 and 115 may include an edge portion 114 disposed on the sixth surface 6 of the main body 110 and an edge portion 115 disposed on the fifth surface 5 of the main body 110. For example, the

edge portions

114 and 115 may be provided on both side surfaces of the main body 110 opposite to each other in the width direction.

As shown in fig. 3, the

rim portions

114 and 115 may refer to regions between the ends of the first and second

internal electrodes

121 and 122 in a cross section of the body 110 cut in a width-thickness (WT) direction and the outer surface of the body 110.

The

edge portions

114 and 115 may substantially serve to prevent damage to the inner electrodes due to external physical or chemical stress.

The

edge portions

114 and 115 may be formed by applying a conductive paste for forming internal electrodes in regions of the ceramic green sheets other than the edge regions in which the edge portions are formed.

Alternatively or additionally, in order to suppress the step difference caused by the

internal electrodes

121 and 122, after the stacking operation, the internal electrodes may be cut to be exposed from the fifth and sixth surfaces 5 and 6 of the body. Then, a single dielectric layer or two or more dielectric layers may be stacked on both exposed surfaces of the capacitance forming part a in the width direction to form the

edge parts

114 and 115.

The

internal electrodes

121 and 122 may be alternately stacked with the dielectric layer 111.

The

internal electrodes

121 and 122 may include a first internal electrode 121 and a second internal electrode 122. The first and second

internal electrodes

121 and 122 may be alternately disposed to face each other and to overlap each other with the dielectric layer 111 constituting the body 110 interposed between the first and second

internal electrodes

121 and 122, and the first and second

internal electrodes

121 and 122 may be exposed from the third and

fourth surfaces

3 and 4 of the body 110, respectively.

Referring to fig. 2, the first internal electrode 121 may be configured to be spaced apart from the fourth surface 4 and exposed from the third surface 3, and the second internal electrode 122 may be configured to be spaced apart from the third surface 3 and exposed from the fourth surface 4.

In this case, the first and second

internal electrodes

121 and 122 may be electrically separated from each other by the dielectric layer 111 interposed therebetween.

Referring to fig. 3, the body 110 may be formed by alternately stacking ceramic green sheets on which the first internal electrodes 121 are printed and ceramic green sheets on which the second internal electrodes 122 are printed, and then firing the stacked ceramic green sheet stack.

The material for forming the

internal electrodes

121 and 122 is not particularly limited, and a material having excellent conductivity may be used. For example, the

internal electrodes

121 and 122 may be formed by printing a conductive paste for internal electrodes, which includes one or more of nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), and alloys thereof, on a ceramic green sheet.

As a printing method of the conductive paste for the internal electrode, a screen printing method, a gravure printing method, or the like may be used, but the present disclosure is not limited thereto.

In order to achieve miniaturization and high capacitance of the multilayer ceramic capacitor, the thicknesses of the dielectric layers and the internal electrodes should be thinned to increase the number of stacked layers. However, when the thicknesses of the dielectric layer and the internal electrode are thinned, reliability may be deteriorated, and characteristics such as insulation resistance, breakdown voltage, and the like may be deteriorated.

Therefore, as the thicknesses of the dielectric layer and the internal electrode become thinner, the effect of improving reliability according to the present disclosure may increase.

In particular, when the thickness (te) of the

internal electrodes

121 and 122 or the thickness (td) of the dielectric layer 111 is 0.41 μm or less, the effect of improving the high temperature life characteristic and the TCC characteristic according to the present disclosure may be significant. For example, in a region of the dielectric layer 111 disposed at a distance of 0.41 μm or less from both the first and second

internal electrodes

121 and 122, 50% or more of the total number of dielectric grains in the dielectric layer 111 may have a core-double shell structure having a core, a first shell having a different composition from the core and surrounding at least a portion of the core, and a second shell having a different composition from the first shell and surrounding at least a portion of the first shell. For example, in a region of the dielectric layer 111 disposed at a distance of 0.41 μm or less from both the first and second

internal electrodes

121 and 122, at least one of the dielectric grains of the dielectric layer 111 may have a core-shell structure having a core and a first shell surrounding at least a portion of the core and having a concentration of the rare earth element higher than that of the core.

The thickness (te) of the

internal electrodes

121 and 122 may refer to an average thickness of the first and second

internal electrodes

121 and 122.

The thickness (te) of the

internal electrodes

121 and 122 may be measured by scanning an image of a section (L-T section) of the body 110 in the third direction and the first direction by a Scanning Electron Microscope (SEM).

For example, based on the reference inner electrode layers at the points where the center line in the length direction of the body and the center line in the thickness direction of the body intersect, the thickness (te) of the

inner electrodes

121 and 122 may be determined by the following method: two points on the left and two points on the right are defined at equal intervals from a reference center point in the reference inner electrode layer, and among the inner electrode layers extracted from images of sections (L-T sections) in the third and first directions of the center portion of the main body 110 scanned by a Scanning Electron Microscope (SEM) of the main body 110 cut in the width direction, the thicknesses of five inner electrode layers including the reference inner electrode layer, two upper inner electrode layers and two lower inner electrode layers respectively arranged above and below the reference inner electrode layer at each of the defined points are measured, and an average value is obtained therefrom.

For example, since the thickness at the reference center point in the reference inner electrode layers at the point where the center line in the longitudinal direction of the main body and the center line in the thickness direction of the main body of the above five inner electrode layers intersect can be measured, and the thickness at each of the left two points and the right two points at equal intervals (each 500nm) from the reference center point, the thickness (te) of the

inner electrodes

121 and 122 can be determined as the average value of the thicknesses of 25 points in total.

The thickness (td) of the dielectric layer 111 may refer to an average thickness of the dielectric layer 111 disposed between the first and second

internal electrodes

121 and 122.

The thickness (td) of the dielectric layer 111 may be measured by scanning an image of a section (L-T section) of the main body 110 in the third direction and the first direction by a Scanning Electron Microscope (SEM), similar to the thickness (te) of the inner electrode.

For example, based on the reference dielectric layer at a point where a center line in the length direction of the body and a center line in the thickness direction of the body intersect, the thickness (td) of the dielectric layer 111 can be determined by: two points on the left and two points on the right are defined at equal intervals from a reference center point in the reference dielectric layer, and of the dielectric layers extracted from images of sections (L-T sections) in the third and first directions of the central portion of the main body 110 in the width direction, which is cut by a Scanning Electron Microscope (SEM), of the main body 110, the thicknesses of five dielectric layers including the reference dielectric layer, two upper dielectric layers and two lower dielectric layers respectively disposed above and below the reference dielectric layer at each of the defined points are measured, and an average value is obtained therefrom.

For example, since the thickness at the reference center point in the reference dielectric layer at the point where the center line in the longitudinal direction of the main body and the center line in the thickness direction of the main body of the above five dielectric layers intersect can be measured, and the thickness at each of the left two points and the right two points at equal intervals (each 500nm) from the reference center point, the thickness (td) of the dielectric layer 111 can be determined as an average value of the thicknesses of 25 points in total.

The

outer electrodes

131 and 132 may be disposed on the body 110 and may be connected to the

inner electrodes

121 and 122, respectively.

As shown in fig. 2, the first and second

external electrodes

131 and 132 may be disposed on the third and

fourth surfaces

3 and 4 of the body 110, respectively, and may be connected to the first and second

internal electrodes

121 and 122, respectively.

In the present embodiment, a structure in which the ceramic electronic component 100 has two

external electrodes

131 and 132 may be described, but the number, shape, etc. of the

external electrodes

131 and 132 may be changed according to the shape of the

internal electrodes

121 and 122 or other purposes.

The

external electrodes

131 and 132 may be formed using any material as long as they have conductivity, such as metal, specific materials may be determined in consideration of electrical characteristics, structural stability, and the like, and the

external electrodes

131 and 132 may have a multi-layered structure.

For example, the

external electrodes

131 and 132 may include

electrode layers

131a and 132a and plating

layers

131b and 132b formed on the

electrode layers

131a and 132a, respectively.

As more specific examples of the

electrode layers

131a and 132a, the

electrode layers

131a and 132a may be sintered electrodes including conductive metal and glass, or may be resin-based electrodes including conductive metal and resin.

In addition, the

electrode layers

131a and 132a may have a form in which a sintered electrode and a resin-based electrode are sequentially formed on the main body 110. In addition, the

electrode layers

131a and 132a may be formed by transferring a sheet including a conductive metal onto the body 110, or may be formed by transferring a sheet including a conductive metal onto a sintered electrode.

The conductive metal used for the

electrode layers

131a and 132a is not particularly limited as long as it is a material that can be electrically connected to the internal electrodes to form a capacitor. For example, the conductive metal may be one or more of nickel (Ni), copper (Cu), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), and alloys thereof.

The plating layers 131b and 132b may be plating layers including one or more of nickel (Ni), tin (Sn), palladium (Pd), and an alloy thereof, and may be formed using a plurality of layers.

As more specific examples of the plating layers 131b and 132b, the plating layers 131b and 132b may be nickel (Ni) plating layers or tin (Sn) plating layers, may have a form in which a nickel (Ni) plating layer and a tin (Sn) plating layer are sequentially formed on the

electrode layers

131a and 132a, and may have a form in which a tin (Sn) plating layer, a nickel (Ni) plating layer, and another tin (Sn) plating layer are sequentially formed. In addition, the plating layers 131b and 132b may include a plurality of nickel (Ni) plating layers and/or a plurality of tin (Sn) plating layers.

Method for manufacturing ceramic electronic component

Hereinafter, a method of manufacturing a ceramic electronic component according to another aspect of the present disclosure will be described in detail. However, in order to avoid repetitive descriptions, descriptions overlapping with those described in the ceramic electronic component will be omitted.

According to another aspect of the present disclosure, a method of manufacturing a ceramic electronic component includes: preparing a base material powder having a core-shell structure having a core and a shell, the shell including a rare earth element; adding a secondary component to the base material powder to prepare a ceramic green sheet; printing a conductive paste for internal electrodes on the ceramic green sheets, and then stacking the printed ceramic green sheets to prepare a stacked body; firing the stacked body to prepare a body including a dielectric layer and an internal electrode; and forming an external electrode on the main body, wherein an amount of the rare earth element included in the base material powder is more than 0.6 times and less than 2.4 times an amount of the rare earth element included in the minor component.

First, a base material powder having a core-shell structure having a core and a shell including a rare earth element may be prepared.

When the base material powder does not have a core-shell structure, it may be difficult to realize the dielectric crystal grain having a core-double shell structure according to the present disclosure.

The method of producing the base material powder having the core-shell structure is not particularly limited. For example, when BaTiO is produced by hydrothermal synthesis₃In this case, the rare earth element may be added in a process of growing the powder to a desired size to synthesize the base material powder. Optionally, in the presence of BaTiO₃After mixing with the rare earth elements, a base material powder having a core-shell structure can be manufactured by heat treatment.

Next, the minor components may be added to the base material powder to prepare a ceramic green sheet. In this case, after the minor components are added to the base material powder, ethanol and toluene as solvents may be mixed with the dispersant, and a binder may be further mixed therewith to manufacture a ceramic green sheet.

In order to realize the dielectric crystal grain having the core-double shell structure according to the present disclosure, the amount of the rare earth element included in the base material powder may be controlled to be more than 0.6 times to less than 2.4 times the amount of the rare earth element included in the secondary component.

When the amount of the rare earth element included in the base material powder is 0.6 times or less the amount of the rare earth element included in the secondary component, the dielectric properties may be deteriorated. When the amount of the rare earth element included in the matrix material powder is 2.4 times or more the amount of the rare earth element included in the minor component, it may be difficult to achieve the dielectric crystal grain having the core-double shell structure according to the present disclosure.

Therefore, the amount of the rare earth element included in the base material powder is preferably more than 0.6 times and less than 2.4 times, more preferably, more than or equal to 0.7 times and less than or equal to 2.2 times, and even more preferably, more than or equal to 0.8 times and less than or equal to 2.0 times the amount of the rare earth element included in the minor component.

In addition, the elements (other than the rare earth elements) included in the minor component are not particularly limited, and the elements included in the minor component may be appropriately controlled to obtain desired characteristics.

Next, after printing a conductive paste for internal electrodes on the ceramic green sheets, a plurality of the printed ceramic green sheets may be stacked to prepare a stacked body.

Next, the stacked body may be fired to prepare a body including the dielectric layer and the internal electrode.

In this case, the dielectric layer may include a plurality of dielectric grains, at least one of the plurality of dielectric grains may have a core-double shell structure having a core and a double shell, the double shell may include a first shell surrounding at least a portion of the core and a second shell surrounding at least a portion of the first shell, and a concentration of the rare earth element included in the second shell may be greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

In addition, in order to make the concentration of the rare earth element included in the second shell more than 1.3 times and less than 3.8 times the concentration of the rare earth element included in the first shell, the firing temperature and the amount of the rare earth element added to the base material powder and the secondary component are appropriately adjusted.

The specific numerical range of the firing temperature may vary depending on the type and amount of the additional element, but is not particularly limited. For example, the firing temperature may range from greater than 1230 ℃ to less than 1280 ℃.

Next, external electrodes may be formed on the body to obtain a ceramic electronic component.

Examples of the invention

The base material powders shown in table 1 below were prepared. In this case, "BT doped with 1.2 Dy" means BT having a core-shell structure (having a core and a shell) and containing 1.2 moles of Dy (to 100 moles of BaTiO) in the shell₃Compared) to the base material powder. In addition, "BT doped with 0.5 Dy" means BT having a core-shell structure (having a core and a shell) and containing 0.5 mol of Dy (to 100 mol of BaTiO) in the shell₃Compared) to the base material powder. In addition, "undoped BT" refers to BaTiO having no core-shell structure₃And (3) powder. Here, BT represents BaTiO₃I.e. matrix material powder.

Thereafter, the minor components listed in table 1 below were added to the base material powder, mixed with a dispersant using ethanol and toluene as solvents, and then further mixed with a binder to prepare a ceramic green sheet. Ni electrodes were printed on the prepared ceramic green sheets, and a plurality of the printed ceramic green sheets were stacked, pressed, and cut to prepare a plurality of sheets. The sheet was fired to remove the binder, and then a firing operation was performed at firing temperatures shown in table 1 below under a reducing atmosphere to prepare sample sheets.

The dielectric constant, 125 ℃ TCC value and high temperature life characteristics of the prepared sample pieces were measured and recorded in Table 2 below.

125 ℃ TCC values were measured at 1kHz and 1V using an LCR meter (capacitance inductance resistance meter) over a temperature range of-55 ℃ to 125 ℃.

The test of the high temperature life characteristics (high temperature IR lift test) was performed by holding 40 samples for each test number under conditions including 150 ℃ and 1Vr ═ 10V/μm for 30 minutes, increasing the voltage by a multiple, and calculating the average value of the voltage values. In this case, "1 Vr" refers to a 1 reference voltage, and "10V/μm" refers to a voltage of 10V per 1 μm dielectric thickness.

Further, the sample pieces were analyzed by a Transmission Electron Microscope (TEM) and an energy dispersive X-ray spectroscopy (EDS) apparatus for cross sections (L-T cross sections) in the longitudinal direction and the thickness direction, which were cut at the central portion in the width direction of each of the sample pieces, to show concentrations, lengths, and fractions in table 2 below. A200 kV ARM was used as TEM and was measured 4,100,000 times with spots (spot). STEM-EDS was measured at 100 points at 10nm intervals.

Concentration was determined by: the crystal grain having the core-double shell structure is subjected to energy dispersive X-ray spectroscopy (EDS) line analysis mounted on a Transmission Electron Microscope (TEM), and a value of subtracting the Dy intensity of the core from the Dy intensity of the second shell is divided by a value of subtracting the Dy intensity of the core from the Dy intensity of the first shell.

Length is determined by: TEM EDS line analysis was performed on the crystal grains having the core-double shell structure as shown in fig. 7, and shows the results of [ the number of points measured in LS2 ]/[ the total number of points measured from α to β ].

Score is determined by: in a 10 μm × 10 μm region in the central portion in the length direction and the thickness direction of the cross section (L-T cross section), the ratio of the number of crystal grains having a core-double shell structure to the total number of dielectric crystal grains was measured.

[ Table 1]

[ Table 2]

Test No. 2, test No. 3, test No. 8, and test No. 9 confirm that the concentration of the rare earth element included in the second shell satisfies 1.3 times or more and less than 3.8 times the concentration of the rare earth element included in the first shell to provide excellent reliability of the high-temperature lifetime characteristic. In addition, test No. 2, test No. 3, test No. 8 and test No. 9 confirmed that their dielectric constants and 125 ℃ TCC characteristics were excellent.

The test No. 11 and the test No. 12, which did not include crystal grains having a core-double shell structure, were inferior in reliability of high-temperature life characteristics.

In addition, test No. 1, test No. 5 to test No. 7, and test No. 10, which include crystal grains having a core-double shell structure but include the rare earth element in the second shell at a concentration 1.3 times or less or 2.8 times or more the concentration of the rare earth element included in the first shell, are inferior in reliability of the high-temperature life characteristics.

In particular, the test No. 1 and the test No. 4 were confirmed to be inferior in reliability of high-temperature life characteristics with respect to the test No. 11 having the same composition and no core-double shell structure, and the test No. 7 was confirmed to be inferior in reliability of high-temperature life characteristics with respect to the test No. 12 having the same composition and no core-double shell structure. Therefore, it can be seen that the reliability of the high temperature lifespan characteristics can be significantly improved by controlling the concentration of the rare earth element included in the second shell to satisfy more than 1.3 times and less than 3.8 times the concentration of the rare earth element included in the first shell.

Fig. 7 shows measured Dy intensity as a result of XRF EDS line analysis of grains having a core-double shell structure of test No. 9 (inventive example).

In fig. 7, the intensity of Dy in the distance (LC) corresponding to the core is about 25 on average, which indicates that Dy is not present therein. The intensity of Dy in the distance (LC) corresponding to the core may vary depending on the TEM facility and the measurement condition environment, but a portion having the lowest value of the measured intensity may be considered as the core, and Dy may not be present in the core.

The intensity of Dy in the distance (LS1) corresponding to the first shell is about 51 on average, and the intensity of Dy in the distance (LS2) corresponding to the second shell is about 64 on average. Therefore, since the value of the Dy intensity by which the core is subtracted from the Dy intensity of the second shell is 1.5 times the value of the Dy intensity by which the core is subtracted from the Dy intensity of the first shell, the concentration of the rare earth element included in the second shell is 1.5 times the concentration of the rare earth element included in the first shell. The intensity of Dy in the distance corresponding to the first shell (LS1) and the intensity of Dy in the distance corresponding to the second shell (LS2) may also vary depending on the TEM facility and the measurement condition environment, but the concentration ratio of the rare earth element between the first shell and the second shell may be maintained.

According to an aspect of the present disclosure, a ceramic electronic component includes: a body including a dielectric layer and an internal electrode; and an outer electrode disposed on the body and connected to the inner electrode, wherein the dielectric layer includes a plurality of dielectric crystal grains, wherein at least one of the plurality of dielectric crystal grains has a core-double shell structure having a core and a double shell, wherein the double shell has a first shell surrounding at least a portion of the core and a second shell surrounding at least a portion of the first shell, wherein a concentration of the rare earth element included in the second shell is more than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

According to another aspect of the present disclosure, a method of manufacturing a ceramic electronic component includes: preparing a base material powder having a core-shell structure having a core and a shell, the shell including a rare earth element; adding a secondary component to the base material powder to prepare a ceramic green sheet; printing a conductive paste for internal electrodes on the ceramic green sheets, and then stacking the printed ceramic green sheets to prepare a stacked body; firing the stacked body to prepare a body including the dielectric layer and the internal electrode; and forming an external electrode on the main body, wherein an amount of the rare earth element included in the base material powder is more than 0.6 times and less than 2.4 times an amount of the rare earth element included in the secondary component.

According to the ceramic electronic component of the present disclosure, it is possible to improve reliability, improve Temperature Coefficient of Capacitance (TCC) characteristics, improve high temperature life characteristics, and improve dielectric constant.

While embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the scope of the disclosure as defined by the appended claims.

Claims

1. A ceramic electronic component comprising:

a body including a dielectric layer and an internal electrode; and

an outer electrode disposed on the body and connected to the inner electrode,

wherein the dielectric layer comprises a plurality of dielectric grains,

wherein at least one of the plurality of dielectric crystal grains has a core-double shell structure having a core and a double shell,

wherein the double shell comprises a first shell surrounding at least a portion of the core and a second shell surrounding at least a portion of the first shell, and

wherein a concentration of the rare earth element included in the second shell is more than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

2. The ceramic electronic component of claim 1, wherein a thickness of the second shell along a line connecting α and β is greater than 4% and less than 25% of a distance between α and β, where α represents a center of the core-double shell structure in a cross-section of the core-double shell structure, and β represents a point on a surface of the second shell farthest from α.

3. The ceramic electronic component according to claim 2, wherein a thickness of the first shell along a straight line connecting α and β is 5% to 30% of a distance between α and β.

4. The ceramic electronic component according to claim 2, wherein a thickness of the first case along a straight line connecting α and β is 0.5 to 1.5 times a thickness of the second case along a straight line connecting α and β.

5. The ceramic electronic component according to claim 1, wherein a concentration of a rare earth element included in the core of the core-double shell structure is 0.1 times or less a concentration of a rare earth element included in the first shell.

6. The ceramic electronic component of claim 1, wherein the first shell in the core-double shell structure is disposed to cover at least 90% of an area of a surface of the core, and

the second shell in the core-double shell structure is disposed to cover at least 90% of an area of a surface of the first shell.

7. The ceramic electronic component of claim 1, wherein at least one of the plurality of dielectric grains has a core-shell structure.

8. The ceramic electronic component according to claim 1, wherein a total number of the dielectric grains having the core-double shell structure in the dielectric layer is 50% or more of a total number of the plurality of dielectric grains in the dielectric layer.

9. The ceramic electronic component of claim 1, wherein the dielectric layer comprises BaTiO₃、(Ba,Ca)(Ti,Ca)O₃、(Ba,Ca)(Ti,Zr)O₃、Ba(Ti,Zr)O₃And (Ba, Ca) (Ti, Sn) O₃As a main component.

10. The ceramic electronic component according to claim 9, wherein an amount of the rare earth element of the dielectric layer is in a range of 0.1 mol to 15 mol with respect to 100 mol of the main component.

11. The ceramic electronic component of claim 1, wherein the rare earth element is one or more of lanthanum, yttrium, actinium, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and ruthenium.

12. The ceramic electronic component of claim 9, wherein the dielectric layer further comprises one or more of Mn, Cr, Ba, Si, Al, Mg, and Zr as a minor component.

13. A method of manufacturing a ceramic electronic component, the method comprising:

preparing ceramic green sheets each including a base material powder and a secondary component added to the base material powder, the base material powder having a core-shell structure having a core and a shell, and the shell including a rare earth element;

printing a conductive paste for internal electrodes on the ceramic green sheets, and stacking the printed ceramic green sheets to prepare a stacked body;

firing the stacked body to prepare a body including a dielectric layer and an internal electrode; and

an external electrode is formed on the body,

wherein an amount of the rare earth element included in the base material powder is more than 0.6 times and less than 2.4 times an amount of the rare earth element included in the secondary component.

14. The method of claim 13, wherein the dielectric layer comprises a plurality of dielectric grains,

wherein the double shell comprises a first shell surrounding at least a portion of the core-double shell structure and a second shell surrounding at least a portion of the first shell,

15. The method of claim 14, wherein the thickness of the second shell along a line connecting a and β is greater than 4% and less than 25% of the distance between a and β, where a represents the center of the core-double shell structure in a cross-section of the core-double shell structure and β represents the point on the surface of the second shell that is farthest from a.

16. The method of claim 14, wherein a total number of dielectric grains having the core-double shell structure in the dielectric layer is 50% or more of a total number of the plurality of dielectric grains in the dielectric layer.

17. The method of claim 14, wherein the firing is performed at a firing temperature such that a concentration of the rare earth element included in the second shell is greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

18. The method of claim 13, wherein the firing operation is performed at a firing temperature range of greater than 1230 ℃ to less than 1280 ℃.

19. A ceramic electronic component comprising:

a body including first and second internal electrodes stacked on each other with a dielectric layer disposed therebetween,

wherein, in a region of the dielectric layer disposed 0.41 μm or less from both the first and second internal electrodes, 50% or more of a total number of dielectric grains in the dielectric layer have a core-double shell structure having a core, a first shell having a different composition from the core and surrounding at least a portion of the core, and a second shell having a different composition from the first shell and surrounding at least a portion of the first shell.

20. The ceramic electronic component of claim 19, wherein a concentration of the rare earth element of each of the first and second shells is higher than a concentration of the rare earth element of the core.

21. The ceramic electronic component of claim 19, wherein a concentration of the rare earth element included in the second shell is greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

22. The ceramic electronic component of claim 19, wherein a thickness of the second shell along a line connecting a and β is greater than 4% and less than 25% of a distance between a and β, where a represents a center of the core-double shell structure in a cross-section of the core-double shell structure and β represents a point on a surface of the second shell farthest from a.

23. The ceramic electronic component of claim 19, wherein the 100 moles of BaTiO are included₃、(Ba,Ca)(Ti,Ca)O₃、(Ba,Ca)(Ti,Zr)O₃、Ba(Ti,Zr)O₃And (Ba, Ca) (Ti, Sn) O₃Has an amount of a rare earth element in a range of 0.1 mol to 15 mol.

24. A ceramic electronic component comprising:

wherein, in a region of the dielectric layer disposed at a distance of 0.41 μm or less from both the first and second internal electrodes, at least one of the dielectric crystal grains of the dielectric layer has a core-shell structure having a core and a first shell surrounding at least a portion of the core and having a concentration of the rare earth element of the first shell higher than a concentration of the rare earth element of the core.

25. The ceramic electronic component of claim 24, wherein at least one of the dielectric grains of the dielectric layer has a core-double shell structure including a core, a first shell surrounding at least a portion of the core, and a second shell surrounding at least a portion of the first shell and having a different composition than the first shell, and

the concentration of the rare earth element of the second shell is higher than that of the first shell.

26. The ceramic electronic component of claim 25, wherein a concentration of the rare earth element included in the second shell is greater than 1.3 times and less than 3.8 times a concentration of the rare earth element included in the first shell.

27. The ceramic electronic component of claim 25, wherein a thickness of the second shell along a line connecting a and β is greater than 4% and less than 25% of a distance between a and β, where a represents a center of the core-double shell structure in a cross-section of the core-double shell structure and β represents a point on a surface of the second shell farthest from a.